Diesel engine applications, especially for passenger cars, at this time are not yet able to make adjustments, during current operation, that are dependent upon fuel quality. In markets having very great quality differences, such as in the USA, in response to poor Diesel quality, considerable deterioration may therefore occur in the emissions and in running smoothness, under certain circumstances. In the extreme case this leads to an unacceptable nuisance to the vehicle users because of the bad smell and the lack of running smoothness.
Mass-produced cylinder pressure sensors are now under development, which make combustion evaluation possible. New sheathed-element glow plugs made of ceramic enable ignition almost as frequently as desired during engine operation.